A compound used to form the matrix for MALDI (matrix-assisted laser desorption/ionization) mass spectrometry. MALDI matrix materials are crystalline compounds with a fairly low molecular weight, so as to allow facile vaporization, have strong absorption at UV or IR wavelengths (to rapidly and efficiently absorb laser irradiation), generally contain polar groups (enabling them to be used in aqueous solutions) and are frequently acidic (so assisting ionisation of the compound being studied, which is contained within the matrix material).